I updated two L4 installs from 4.0a SR-3 to 4.0b Beta 6, and one received a new PericopeSets.lbspsd file (dated 1/13/2010 12:25:50 AM), and the other has an older version of the file (10/27/2009 4:51:14 PM).
Let me know if I need to provide any additional information!
Thanks